Hi
I replied to this before but my usual ID is still zapped due to over posting, so it will appear again when the techies get a grip, but in the meantime i have copied and pasted my reply here from my user profile:
Trade Directories tend to come in two forms, the large comprehensive nationally produced ones by Slaters and Pigots or similar, and then the more locally compiled and distributed ones done mainly by the local newspapers. Copies of both types, which tended to be published erratically, should be found in the local reference libraries
http://www.genuki.org.uk/big/eng/ncl/TradeDir2 .html
The bigger directories that covered households and individuals also survive and so it is worth looking at these to see if the photographer had a seperate residence from the shop.
The other source would be the 1901 census return, the address would be listed if it was residential, you should look at the other residents of the street to see if it is mainly housing as opposed to business to get an idea on whether the business was based in his home.
If it is the family itself you are interested in, it is worth loking at the GRO index for B, M & D, for that period, any instances of that surname registering in Newcastle may lead you to a certificate containing further info.
Dotty